: : I am trying to sell a home that an inspector says has a slow tub drain. It doesn't seem slow to me. Is there any standard test that can be used to provide an impartial result such as how long it would take to drain 10 gallons of water for example?

: Yes, Jim there is a "Standard"

: A fixture unit is 7.48 gallons a bath tub is equal to TWO FU's (11/2" trap)

: A fixture unit is the amount of water that can drain/fill in a given amount of time.

: Normally a basin is considered ONE FU and its should take about ONE minute to drain THUS a TWO fixture unit should take about two minutes to drain.

: If it gurgles try getting the drain line water jetted to remove build up soap scum.